1. Field of the Invention
The present invention relates a method of forming a fine particle array on a substrate utilizing a hollow protein. Further, the present invention relates to a semiconductor element utilizing the fine particle array.
2. Description of the Related Art
There were conventional methods of forming fine particles which comprise fixing a protein complex, which can include a fine particle therein, on a substrate; removing the protein by a heat treatment or the like; and reducing in a reducing atmosphere to produce a metal atom aggregate (for example, see, Japanese Patent Provisional Publications No. 2002-223016, No. H11-45990 and No. H11-233752).
FIG. 2 shows a conventional method of forming fine particles described in Japanese Patent Provisional Publications No. 2002-223016 and No. H11-233752; FIG. 3 shows a conventional method of forming fine particles described in Japanese Patent Provisional Publication No. H11-45990; and FIG. 4 shows a conventional method of forming fine particles described in Japanese Patent Provisional Publication No. H11-233752, respectively.
In FIG. 2A and FIG. 3A, protein complexes (ferritin) 4 including a fine particle therein are dispersed in an aqueous solution in a water bath 3. Next, when a polypeptide film (PBLH) 5 is formed on the surface of water, the aforementioned protein complexes 4 are adsorbed onto the polypeptide film 5 to form a high density monolayer film on surface of the aqueous solution (FIG. 2B and FIG. 3B). Next, by bringing a substrate 6 into contact with this surface of water, the monolayer film of the protein complexes 4 is transferred to the substrate 6 (FIG. 2C and FIG. 3C), thereby allowing high density fine particles to be fixed on the substrate (FIG. 2D and FIG. 3D).
In Japanese Patent Provisional Publications No. 2002-223016 and No. H11-233752, protein components are thereafter eliminated by subjecting the substrate to a heat treatment in an inert gas (nitrogen) atmosphere. In Japanese Patent Provisional Publication No. H11-45990, the protein components are eliminated by subjecting the substrate 6 to an ozone treatment at 100° C. to 150° C. as shown in FIG. 3E to form iron oxide fine particles 8 on the substrate (FIG. 3F).
Although not shown in the Figure, in Japanese Patent Provisional Publications No. 2002-223016, No. H11-45990 and No. H11-233752, reduction is thereafter executed by subjecting to a heat treatment in hydrogen at 300 to 500° C. to form iron atom aggregates (metal fine particles).
In the method of manufacturing a semiconductor element disclosed in Japanese Patent Provisional Publication No. H11-233752, metal oxide fine particles, and protein complexes 204 comprising a hollow protein including a metal oxide fine particle therein (hereinafter, referred to as “protein complex”) are first arranged on a gate oxidized film 203, as shown in FIG. 4A. Next, the hollow protein is removed, and then the metal oxide fine particles are subjected to a reduction treatment. Thereafter, as shown in FIG. 4B, a silicon oxidized film is further formed with a CVD method, and a semiconductor element having metal fine particles is formed by embedding the reduced metal fine particles into the silicon oxidized film.